Devserver: only populate data during cron jobs, meaning all data from instances

chrome/common/extensions/docs/server2/persistent_object_store.py

+# Copyright 2013 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+from appengine_wrappers import db
+import cPickle
+from future import Future
+import logging
+from object_store import ObjectStore
+
+# XXX(kalman): this appears to be global somehow. I don't know.
+# Figure it out.
+class _Item(db.Model):
+  '''The generic data store model to use for all model types.
+  '''
+  key_ = db.StringProperty()
+  pickled_value = db.BlobProperty()
+
+class _AsyncGetFuture(object):
+  def __init__(self, object_store, keys):
+    self._object_store = object_store
+    self._futures = dict((k, db.get_async(object_store._ToItemKey(k)))
+                         for k in keys)
+
+  def Get(self):
+    def has_result(key, future):
+      item_key = self._object_store._ToItemKeyPath(key)
+      if future.get_result() is not None:
+        logging.warning('%s HAS a value!' % item_key)
+        return True
+      else:
+        logging.warning('%s has no value' % item_key)
+        return False
+    return dict((key, cPickle.loads(future.get_result().pickled_value))
+                for key, future in self._futures.iteritems()
+                if has_result(key, future))
+
+class PersistentObjectStore(ObjectStore):
+  '''Stores data persistently using the AppEngine Datastore API.
+  '''
+  def __init__(self, namespace):
+    self._namespace = namespace
+
+  def SetMulti(self, mapping):
+    futures = []
+    for k, v in mapping.items():
+      logging.warning('Setting %s' % self._ToItemKeyPath(k))
+      item = _Item(key_=self._ToItemKeyPath(k),

[方觉(Fang Jue), 2013/04/16 14:26:49]

you probably need to use key_name=... here so that
db.get_async(object_store._ToItemKey(k)) will work. (and key_ may or may not be
necessary)
See also
https://developers.google.com/appengine/docs/python/datastore/modelclass#Model
and related docs about keys of entities.

+                   pickled_value=cPickle.dumps(v))
+      futures.append(db.put_async(item))
+    for future in futures:
+      future.wait()

[方觉(Fang Jue), 2013/04/16 14:26:49]

why not use synchronous api here?

[not at google - send to devlin, 2013/04/17 18:00:50]

So that while each of these is wait()ing the other put_async()s are running. In
any case, I've put this behind an IsDevServer flag.

+
+  def GetMulti(self, keys):
+    # XXX(kalman): make this work:
+    return Future(delegate=_AsyncGetFuture(self, keys))
+
+  def DelMulti(self, keys):
+    futures = []
+    for key in keys:
+      futures.append(db.delete_async(self._ToItemKey(key)))
+    for future in futures:
+      future.wait()
+
+  def _ToItemKey(self, key):
+    # XXX(kalman): users of this method aren't working. Ugh.
+    return db.Key.from_path('_Item', self._ToItemKeyPath(key))
+
+  def _ToItemKeyPath(self, key):
+    return '%s/%s' % (self._namespace, key)